1. Field of the Invention
The present invention relates to a wireless communication, more particularly, to a method for logging measurement results in a wireless communication and an apparatus supporting the same.
2. Related Art
3rd generation partnership project (3GPP) long term evolution (LTE) is an improved version of a universal mobile telecommunication system (UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPP LTE.
Minimization of driving tests (MDT) is a test performed by service providers for coverage optimization by using user equipment (UE) instead of using an automobile. Coverage varies depending on the location of a base station (BS), the arrangement of buildings nearby, and the usage environment of a user. Therefore, it is required for the service providers to periodically perform the driving test, and a lot of costs and resources are consumed. The MDT is used when a service provider measures coverage by using UE.
The service provider collects measurement results reported from a plurality of UEs to create a coverage map showing service availability and distribution of service quality in all areas of services. For example, if the service provider receives a report about the problem of coverage in a particular area from the UE, it may extend the coverage of cells in that area by increasing the transmission power of the base station which provides service to that area.
In the MDT method, the UE may log a plurality of measurement results and report the logged measurements to the network. The measurement and logging by the UE may be performed periodically or based on a specific event. Available storage space for the UE to log measurement results is limited. If the UE performs measurement and logging a plurality of times, there may be no storage space left for logging, and subsequently the UE may not performed further measurement/logging. Therefore, there is a need for discussion about the measurement result logging method to be performed by the UE, in relation to limited storage space for the UE's logging.